Speaker diaphragm and speaker

ABSTRACT

The present disclosure provides a speaker diaphragm and a speaker. The diaphragm includes two surface layers compounded together and at least one intermediate layer located between the two surface layers, wherein at least one of the surface layers is a thermoplastic polyester elastomer film layer, at least one of the intermediate layers is an adhesive layer, a thermoplastic polyester elastomer is a copolymer composed of a polyester hard segment A and a polyether or aliphatic polyester soft segment B, a thickness of the thermoplastic polyester elastomer film layer is 5-70 μm, and a thickness of the adhesive layer is 1-40 μm.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a National Stage of International Application No.PCT/CN2018/110164, filed on Oct. 13, 2018, which claims priority toChinese Patent Application No. 201810623919.4, filed on Jun. 15, 2018,both of which are hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to the technical field of electro-acousticconversion, and more specifically to a speaker diaphragm and a speaker.

BACKGROUND

Existing speaker diaphragms mostly adopt a composite structure of highmodulus plastic substrate layers (PEEK, PAR, PEL, PI, etc.), softthermoplastic polyurethane elastomer (TPU) and damping film (acrylicglue, silica gel, etc.). The overall performance of the above-mentioneddiaphragm is poor, which is likely to cause poor sound quality.

With the improvement of high power, waterproof and high sound qualityrequirements, the diaphragm made from silicone rubber has also beenapplied in the technical field of speakers.

However, the elastic modulus or hardness of silicone rubber isrelatively low. Under the premise of meeting the same F₀ (resonantfrequency) requirements, in order to ensure the strength of thediaphragm, the diaphragm needs to be made thicker. This leads to on onehand a reduced space allowance for vibration and on the other hand aheavy weight of the vibration system, resulting in a lower sensitivity.

Therefore, it is necessary to provide a new technical solution to solvethe above technical problems.

SUMMARY

An object of the present invention is to provide a new technicalsolution for a speaker diaphragm.

According to the first aspect of the present invention, a speakerdiaphragm is provided. The diaphragm comprises two surface layerscompounded together and at least one intermediate layer located betweenthe two surface layers, wherein at least one of the surface layers is athermoplastic polyester elastomer film layer, at least one of theintermediate layers is an adhesive layer, a thermoplastic polyesterelastomer is a copolymer composed of a polyester hard segment A and apolyether or aliphatic polyester soft segment B, a thickness of thethermoplastic polyester elastomer film layer is 5-70 μm, and a thicknessof the adhesive layer is 1-40 μm.

Optionally, the thickness of the thermoplastic polyester elastomer filmlayer is 5-40 μm.

Optionally, the thickness of the adhesive layer is 2-35 μm.

Optionally, a thickness of the speaker diaphragm is 10-100 μm.

Optionally, a loss factor of the thermoplastic polyester elastomer isgreater than or equal to 0.015.

Optionally, an elastic recovery rate of the thermoplastic polyesterelastomer film layer after 10% strain is greater than or equal to 80%,and a percentage of breaking elongation of the thermoplastic polyesterelastomer film layer is greater than or equal to 300%.

Optionally, an adhesive force between the adhesive layer and thethermoplastic polyester elastomer film layer is greater than 100 g/25 mm(180° peeling).

Optionally, a weight percentage of the polyester hard segment A is10-95%, and a relative molecular weight of the polyether or aliphaticpolyester soft segment B is 600-6000;

A material of the polyether or aliphatic polyester soft segment B isselected from one or more of aliphatic polyester, polytetrahydrofuranether, polyphenylene ether and polyethylene oxide, a material of thepolyester hard segment A is a polymer of dibasic acid and dihydricalcohol, wherein the dibasic acid is selected from one or more ofterephthalic acid, isophthalic acid, naphthalenedicarboxylic acid andbiphenyldicarboxylic acid, and the dihydric alcohol is selected from oneor more of ethylene glycol, propylene glycol, butylene glycol,pentanediol, and hexylene glycol.

Optionally, the polyester hard segment A can be crystallized, an averagepolymerization degree of the polyester hard segment A material is ≥2,and a melting temperature of the polyester hard segment A is ≥150° C.

Optionally, the two surface layers are the thermoplastic polyesterelastomer film layers.

Optionally, the speaker diaphragm is of a three-layer structurecomprising one intermediate layer.

Optionally, the speaker diaphragm comprises two intermediate layers, andthe two intermediate layers are adhesive layers of different materials.

Optionally, the speaker diaphragm comprises three intermediate layers,wherein two of the intermediate layers are adhesive layers and the otherintermediate layer is the thermoplastic polyester elastomer film layer,and the thermoplastic polyester elastomer film layer is located betweenthe two adhesive layers; or

The three intermediate layers are all adhesive layers.

Optionally, the thickness of the two surface layers is the same.

According to another aspect of the present invention, a speaker isprovided. The speaker comprises a vibration system and a magneticcircuit system cooperating with the vibration system, wherein thevibration system comprises the speaker diaphragm provided by the presentapplication.

According to an embodiment of the present disclosure, the speakerdiaphragm has both an excellent stiffness and a good dampingperformance, and the like.

The speaker diaphragm has a low Young's modulus and good thermalplasticity, which enables the speaker diaphragm to be made very thin,reduces the weight of the speaker diaphragm, enlarges the allowance forvibration, improves the sensitivity, and makes the F₀ of the speakerlower.

In addition, the speaker diaphragm has a wider elastic region andexcellent resilience performance.

Other features and advantages of the invention will become clear fromthe following detailed description of exemplary embodiments of theinvention with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings incorporated in the specification and constituting a partof the specification illustrate the embodiments of the presentinvention, and together with the description are used to explain theprinciple of the present invention.

FIG. 1A is a SmartPA (smart power amplifier) test curve of aconventional diaphragm.

FIG. 1B is a SmartPA test curve of a speaker diaphragm according to anembodiment of the present invention.

FIGS. 2-4 are cross-sectional views of a speaker diaphragm according toan embodiment of the present invention.

FIG. 5 is a test curve of the vibration displacements of different partsof the speaker diaphragm according to an embodiment of the presentinvention at different frequencies.

FIG. 6 is a test curve of the vibration displacements of different partsof the conventional diaphragm at different frequencies.

FIG. 7 is a cross-sectional view of a speaker diaphragm according to anembodiment of the present invention.

FIG. 8 is a stress-strain curve of a speaker diaphragm according to anembodiment of the present invention and a PEEK diaphragm.

FIG. 9 is a test curve of harmonic distortion between a speakerdiaphragm according to an embodiment of the present invention and aconventional diaphragm.

FIG. 10 is a test curve of loudness (SPL curve) of a speaker diaphragmaccording to an embodiment of the present invention and a conventionaldiaphragm at different frequencies.

DRAWING REFERENCE SIGNS

-   -   11: thermoplastic polyester elastomer film layer; 12: adhesive        layer; 12 a: another adhesive layer; 13: central portion; 14:        FPCB; 16: connecting portion; 17: corrugated rim.

DETAILED DESCRIPTION

Various exemplary embodiments of the invention will now be described indetail with reference to the drawings. It should be noted that: unlessspecifically stated otherwise, the relative arrangement of componentsand steps, numerical expressions, and numerical values set forth inthese embodiments do not limit the scope of the invention.

The following description of at least one exemplary embodiment isactually merely illustrative, and in no way serves as any limitation onthe invention and its application or use.

The technologies, methods, and devices known to those of ordinary skillin the relevant fields may not be discussed in detail, but whereappropriate, the technologies, methods, and devices should be regardedas part of the specification.

In all examples shown and discussed herein, any specific values shouldbe interpreted as exemplary only and not as limitations. Therefore,other examples of the exemplary embodiment may have different values.

It should be noted that similar reference numerals and letters indicatesimilar items in the following drawings, so once an item is defined inone drawing, it does not need to be further discussed in the subsequentdrawings.

According to an embodiment of the present invention, a speaker diaphragmis provided. The diaphragm can be a single-layer structure or acomposite structure composed of a plurality of film layers.

The diaphragm includes a thermoplastic polyester elastomer film layer.The thermoplastic polyester elastomer is a copolymer composed of apolyester hard segment A and a polyether or aliphatic polyester softsegment B.

Specifically, the polyester material and the polyether or aliphaticpolyester material undergo a transesterification reaction to generate acopolymer under the action of a set catalyst. Copolymer is a polymerprepared by linking two or more polymer chain segments with differentproperties together. Due to the inherent incompatibility between thevarious components of the copolymer, it self-assembles into an orderednanostructure in a nanometer scale, and the resulting microphase isseparated, exhibiting the characteristics of having the properties ofdifferent polymer chain segments.

For example, the copolymer raw materials used to make the diaphragm aregranular, powdery, etc. When making the diaphragm, the raw material isheated to form a fluid. The fluid forms the film layer by injectionmolding, tape casting, etc.

The polyester hard segment A has higher hardness and plays a role ofstructural support, which makes the thermoplastic polyester elastomerfilm layer have sufficient stiffness. The polyether or aliphaticpolyester soft segment B has a stronger fluidity and provides compliancefor the film layer, such that the thermoplastic polyester elastomer filmlayer has a good resilience and a low thermoplastic temperature, forexample, which can reach 50° C.-200° C., the molding temperature of thespeaker diaphragm is low, and the processing is easier.

The higher the mass fraction of the polyester hard segment A, the higherthe hardness of the formed speaker diaphragm, but the brittleness of thespeaker diaphragm increases and is easy to break. By contrast, the lowerthe mass fraction of the polyester hard segment A, the more difficultfor the hard segment A of polyester to form crystals, causing thethermoplastic polyester elastomer film layer to have a soft texture andlow hardness, this leads to soft texture and low hardness of thethermoplastic polyester elastomer film and deteriorated toughness andresilience of the speaker diaphragm.

In one example, the mass percentage of the material of the hard segmentA of polyester, that is the percentage of the amount of hard segment Aof polyester material in the total mass of the hard segment A ofpolyester material and the aliphatic polyester soft segment B material(total mass of reactants) is 10-95%. This range allows the speakerdiaphragm to have hardness, toughness and resilience performance.

Preferably, the weight percentage of the material of the polyester hardsegment A is 30-90%. Within this range, the thickness of the speakerdiaphragm can be made thinner, and the hardness, toughness, andresilience performance are better.

Optionally, a material of the polyester hard segment A is a polymer ofdibasic acid and dihydric alcohol. The dibasic acid and the dihydricalcohol undergo the polymerization reaction under the set reactionconditions to form the polyester hard segment A. The polymer easilyreacts with the material of the polyether or aliphatic polyester softsegment B to form a thermoplastic elastomer polymer.

For example, the dibasic acid is selected from one or more ofterephthalic acid, isophthalic acid, naphthalenedicarboxylic acid andbiphenyldicarboxylic acid. The above-mentioned dibasic acid and thedihydric alcohol have a fast reaction speed and a high conversion rate.

For example, the dihydric alcohol is selected from one or more ofethylene glycol, propylene glycol, butylene glycol, pentanediol, andhexylene glycol. The above-mentioned dibasic acid and the dihydricalcohol have a fast reaction speed and a high conversion rate.

Of course, the types of dibasic acids and dihydric alcohol are notlimited to the foregoing embodiments, and can be selected by thoseskilled in the art according to actual needs.

In one example, the polyester hard segment A can be crystallized, andthe average polymerization degree of the polyester hard segment Amaterial is ≥2. With this average polymerization degree, the polyesterhard segment A has a good crystallization property, causing the speakerdiaphragm to have high stiffness, high structural strength and gooddurability.

In one example, the melting temperature of the polyester hard segment Ais ≥150° C. The melting temperature refers to a temperature at which amaterial changes from a solid phase to a liquid phase. The meltingtemperature of the polyester hard segment A determines the meltingtemperature of the thermoplastic polyester elastomer. The higher themelting temperature, the wider the use temperature range of thethermoplastic polyester elastomer. The melting temperature range makesthe application temperature range of the speaker diaphragm wider, whichcan work normally in a higher temperature working environment.

Optionally, the material of the polyether or aliphatic polyester softsegment B is made from a material selected from one or more of aliphaticpolyester, polyethylene oxide, polypropylene oxide, polytetrahydrofuranether, and polyphenylene ether. This enables excellent fluidity of thethermoplastic polyester elastomer and good compliance and flexibility ofthe speaker diaphragm.

In addition, the above-mentioned materials are easy to polymerize withthe material of the polyester hard segment A, such that the processingof the speaker diaphragm becomes easy.

Optionally, the relative molecular weight of the material of thepolyether or aliphatic polyester soft segment B is 600-6000. The lowerthe relative molecular weight of the polyether or aliphatic polyestersoft segment B, the more severe it is dispersed by the polyester hardsegment A, thus the diaphragm exhibits higher brittleness, and thediaphragm has poor toughness and resilience. The higher the relativemolecular weight of the polyether or aliphatic polyester soft segment B,the higher the hardness, and its properties are getting closer andcloser to the polyester hard segment A, which makes the elasticity ofthe speaker diaphragm worse and the percentage of breaking elongationsmaller. The range of the relative molecular mass enables the speakerdiaphragm to have both the sufficient stiffness and toughness, and thehigher tensile strength and greater elongation of broken chain.

In one example, the thickness of the thermoplastic polyester elastomerfilm layer is 5-70 μm. The smaller the thickness of the thermoplasticpolyester elastomer, the less the stiffness of the speaker diaphragm,thus the polarization is likely to occur during vibration. On thecontrary, the larger the thickness, the smaller the space allowance forvibration of the formed vibration system, and meanwhile the weight ofthe vibration system increases, and the sensitivity of the formedvibration system becomes worse. This thickness range enables the speakerdiaphragm to have both the higher stiffness and sensitivity, andenlarges the space allowance for vibration of the vibration system.

Furthermore, the thickness of the thermoplastic polyester elastomer filmlayer is 5-40 μm. This thickness range makes the speaker diaphragm havethe higher sensitivity, and makes likewise the driving power diaphragmhave a large amplitude and great loudness, and enlarges the spaceallowance for vibration of the vibration system.

In addition to providing stiffness in the speaker diaphragm, thethermoplastic polyester elastomer film layer can also provide part ofthe damping performance. This is because the thermoplastic polyesterelastomer film layer is composed of polyester hard segment A andpolyether or aliphatic polyester soft segment B, the molecular chainsegments of polyether or aliphatic polyester soft segment B can move atroom temperature, but the presence of the polyester hard segment A makesthe frictional damping of the molecular chain segment movement large,thus exhibiting good damping characteristics.

The loss factor can characterize the damping amount of the material, andthe loss factor of the thermoplastic polyester elastomer film layer is≥0.015. This shows that the damping of the speaker diaphragm isimproved, the vibration system has a strong ability to suppress thepolarization phenomenon during the vibration process, and the vibrationconsistency is good. The commonly used engineering plastic film layerhas low damping with a loss factor generally less than 0.01, and thedamping is smaller.

Compared with engineering plastics, the thermoplastic polyesterelastomer film layer makes the speaker diaphragm have a wider elasticarea and has good resilience. In one example, the elastic recovery rateof the thermoplastic polyester elastomer film layer after having 10%strain is ≥80%. Due to the good resilience of the speaker diaphragm, thespeaker has a better transient response and a lower distortion.

Commonly used engineering plastic diaphragms, such as PEEK, have a yieldpoint of about 5%, while the thermoplastic polyester elastomer is in ahighly elastic state at room temperature, so it has good resilience, andthe material will not yield significantly when stressed, and there is noyield point or the yield point is >10%.

FIG. 8 shows a stress-strain curve of a speaker diaphragm according toan embodiment of the present invention and a PEEK diaphragm.

Wherein, the dotted line is the stress-strain curve of the speakerdiaphragm provided by the embodiment of the present invention; the solidline is the stress-strain curve of the PEEK diaphragm.

It can be seen from FIG. 8 that under the same stress, the strain of thespeaker diaphragm provided by the embodiment of the present invention issignificantly greater than that of the PEEK diaphragm. This indicatesthat the Young's modulus of the speaker diaphragm provided by theembodiment of the present invention is significantly smaller than thatof the PEEK diaphragm.

In addition, the PEEK diaphragm has an obvious yield point, which isabout 0.4-0.5% strain. However, the speaker diaphragm provided by thepresent invention has no obvious yield point. The strain at yieldis >10%. This shows that the speaker diaphragm provided by the presentinvention has a wider elastic area and has excellent resilienceperformance.

The thermoplastic polyester elastomer film layer makes the speakerdiaphragm have good flexibility, and for example, the percentage ofbreaking elongation is ≥300%. The materials of the polyester hardsegment A and the polyether or aliphatic polyester soft segment B havean important influence on the percentage of breaking elongation, and maybe selected by those skilled in the art according to actual needs. Thismakes the vibration displacement of the speaker diaphragm larger and theloudness greater. And the reliability and durability are good. Thebetter the flexibility of the material, the greater the percentage ofbreaking elongation, and the stronger the ability of the speakerdiaphragm to resist damage. When the speaker diaphragm is vibrating in astate of large amplitude, the material has a relatively large strain,and there is a risk of folding the diaphragm, cracking the diaphragm ordamaging the diaphragm during long-term vibration. The speaker diaphragmwith the thermoplastic polyester elastomer film layer as the basematerial has a good flexibility, which reduces the risk of damaging thediaphragm.

The glass transition temperature of the thermoplastic polyesterelastomer film layer can be adjusted by adjusting the ratio of thepolyester hard segment A material to the polyether or aliphaticpolyester soft segment B material. For example, the weight percentage ofpolyester hard segment A is 10-95%. This makes the glass transitiontemperature of the thermoplastic polyester elastomer film layer ≤20° C.The glass transition temperature enables the speaker diaphragm tomaintain a high elastic state at normal temperature and have a goodresilience.

Preferably, the glass transition temperature of the thermoplasticpolyester elastomer film layer is −90° C.-0° C. This allows the speakerdiaphragm to always maintain better rubber elasticity when it is below0° C., such that the speaker exhibits a higher sound quality. In themeantime, the risk of damaging the speaker diaphragm in a lowtemperature environment is reduced, and the reliability is higher.

The speaker diaphragm of the embodiment of the present invention canmeet the needs of the speaker for use in high and low temperatureenvironments. Its performance is more outstanding than that of theconventional diaphragm (such as PEEK diaphragm) at low temperatures.When used in a low-temperature environment, the diaphragm of theembodiment of the present invention still has good strength andtoughness, and the risk of breaking the diaphragm is low in a long-termlow-temperature environment.

In one example, the Young's modulus of the thermoplastic polyesterelastomer film layer is 1-1000 MPa. In certain conditions, the Young'smodulus is proportional to the F₀ (resonant frequency) of the speaker.The thermoplastic polyester elastomer film layer makes the Young'smodulus of the speaker lower, thereby acquiring a lower F₀, and thusimproving the low-frequency effect of the speaker.

The speaker diaphragm has a low Young's modulus and good thermalplasticity, which allows the speaker diaphragm to be made very thin,thereby reducing the mass of the speaker diaphragm, improving the spaceallowance for vibration, improving the sensitivity and making the F₀ ofthe speaker lower.

The speaker diaphragm has a wider elastic area and an excellentresilience performance.

Further, the Young's modulus of the thermoplastic polyester elastomerfilm layer is 2-700 MPa. As such, the F₀ of the speaker can be furtherreduced. Those skilled in the art can adjust the types, proportions andthe like of the polyester hard segment A material and the polyether oraliphatic polyester soft segment B material according to the soundgeneration requirements of different speaker diaphragms to achieve asuitable Young's modulus.

In one example, the speaker diaphragm is a composite structure. Thecomposite structure includes two surface layers compounded together andat least one intermediate layer located between the two surface layers.At least one surface layer is a thermoplastic polyester elastomer filmlayer, and at least one intermediate layer is an adhesive layer.

The adhesive layer provides the damping and adhesion properties requiredby the speaker diaphragm. The adhesive layer can be directly bonded withthe thermoplastic polyester elastomer film layer to form a compositestructure. This makes the production of the speaker diaphragm very easy.

The loss factor can reflect the magnitude of damping amount. In oneexample, the loss factor of the adhesive layer is ≥0.1. The adhesivelayer can effectively suppress the polarization of the needle-shapedsystem when it vibrates, such that the vibration consistency becomesbetter, thereby improving the hearing effect.

In one example, the adhesive force between the adhesive layer and thethermoplastic polyester elastomer film layer is greater than 100 g/25 mm(180° peeling). The high adhesive force makes the upper and lower filmlayers of the adhesive layer have a good coordination and consistencyduring the vibration process, and the sound quality is pure, and thespeaker diaphragm still maintains the original state after long-termvibration, and the performance stability is high.

Optionally, the adhesive layer is selected from one or more of acrylicadhesives, silicone adhesives and polyurethane adhesives. Theabove-mentioned adhesives have good adhesion and damping properties.Those skilled in the art can make selections according to actual needs.

In this example, the thickness of the adhesive layer is 1-40 μm, and theadhesive force of the adhesive layer increases as the thickness of theadhesive layer increases. If the thickness is too small, the adhesiveforce will be insufficient, and the consistency of the movement of theupper and lower surface layers of the adhesive layer cannot beeffectively guaranteed during the vibration process. In the meantime,the damping effect provided by the adhesive layer will also decrease asthe thickness decreases. The thickness of the adhesive layer is toolarge, thus on one hand reducing the space allowance for vibration, andon the other hand making the edge of the speaker diaphragm prone toproblems such as glue overflow, which affects the process yield. Theadhesive layer in this thickness range can take into account sufficientadhesive force, excellent damping effect and sufficient space allowancefor vibration for the vibration system. Further preferably, thethickness of the adhesive layer is 2-35 μm.

Preferably, the thickness of the speaker diaphragm is 10-100 μm. Thisthickness range enables the vibration system to have sufficient spaceallowance for vibration, and is conducive to the thin and miniaturizeddesign of the speaker.

In one example, as shown in FIG. 2 , the speaker diaphragm has athree-layer structure, which includes an intermediate layer. Theintermediate layer is the adhesive layer 12. The two surface layers arethermoplastic polyester elastomer film layers 11. The speaker diaphragmhas a strong stiffness and a good damping effect.

In addition, the speaker diaphragm has fewer layers, can be madethinner, and has higher vibration sensitivity.

In one example, the two surface layers are thermoplastic polyesterelastomer film layers 11. This makes the hardness, toughness andresilience of the speaker diaphragm better. Since the materials of thetwo surface layers of the diaphragm are uniform, the durability of thediaphragm is more excellent.

In one example, the speaker diaphragm includes two intermediate layers.The two surface layers are thermoplastic polyester elastomer film layers11. Wherein, the two intermediate layers are adhesive layers 12, 12 a ofdifferent materials, as shown in FIG. 3 .

The speaker diaphragm has a strong stiffness and a good damping effect.

In one example, the speaker diaphragm includes three intermediatelayers. The two surface layers are thermoplastic polyester elastomerfilm layers 11. As shown in FIG. 4 , the two intermediate layers areadhesive layers 12, the other intermediate layer is a thermoplasticpolyester elastomer film layer 11, and the thermoplastic polyesterelastomer film layer 11 is located between the two adhesive layers 12.The thermoplastic polyester elastomer film layer 11 and the adhesivelayer 12 are alternately arranged with each other.

The three intermediate layers are adhesive layers 12.

The speaker diaphragm has a strong stiffness, a good damping effect anda good resilience.

Optionally, the Young's modulus of a plurality of thermoplasticpolyester elastomer film layers may be the same or different. Wherein,when the Young's modulus is the same, the vibration consistency of allthermoplastic polyester elastomer film layers is better. When theYoung's modulus is different, the difficulty of up and down vibration ofthe speaker diaphragm can be adapted by adjusting the Young's modulus tooptimize the vibration balance.

In addition, the loss factors and thicknesses of a plurality ofthermoplastic polyester elastomer film layers and adhesive layers may bethe same or different. Those skilled in the art can adjust thestiffness, damping characteristics, compliance, resilience, etc. of thespeaker diaphragm by adjusting the above parameters.

Preferably, the thickness of the two surface layers is the same, whichmakes the speaker diaphragm have a good uniformity and not easy to curlor wrinkle.

When the thermoplastic polyester elastomer mold layer is compounded withthe adhesive layer, the Young's modulus of the formed speaker diaphragmwill change accordingly. The smaller Young's modulus of the adhesivelayer will reduce the Young's modulus of the speaker diaphragm. Forexample, the Young's modulus of the thermoplastic polyester elastomerfilm layer is 1-1000 MPa, and the Young's modulus of the compoundedspeaker diaphragm is 5-600 MPa.

In other examples, one of the two surface layers is a thermoplasticpolyester elastomer film layer, and the other is other materials filmlayer, such as a silicone rubber layer, an engineering plastic layer,and the like. A plurality of film layers are bonded together through theadhesive layer. As such, the speaker diaphragm also has the goodphysical and acoustic properties.

In one example, as shown in FIG. 7 , the speaker diaphragm is acorrugated ring diaphragm, which includes a corrugated rim 17, a centralportion 13 formed by the inner edge of the corrugated rim 17 extendinginwardly, and a connecting portion 16 formed by the outer edge of thecorrugated rim 17 extending outward. For example, a reinforcing layer isprovided in the central portion 13, which can increase the structuralstrength of the speaker diaphragm and reduce the split vibration of thespeaker diaphragm. One end of the voice coil is connected to the centralportion 13. The connecting portion 16 is used to connect with thehousing of the speaker. The thickness of the corrugated rim 17 isconfigured to gradually increase from the apex to a portion close to thecentral portion 13 and the connecting portion 16.

The apex is the highest point or the lowest point of the cross sectionof the corrugated rim 17 in the radial direction. In this way, since thethickness near the apex is smaller, the vibration sensitivity of thespeaker diaphragm is higher. Since the thickness of the portion close tothe central portion 13 and the connecting portion 16 is large, thestructural strength of the diaphragm can be improved.

In one example, as shown in FIG. 7 , the reinforcing layer is FPCB 14.The FPCB 14 is embedded in the central portion 13. The FPCB 14 includesa conductive metal layer and an insulating layer covering the upper andlower sides of the conductive metal layer. The conductive metal layermakes the FPCB 14 have a high strength, and the insulating layer makesthe FPCB 14 have a stronger toughness. FPCB 14 can effectively reducethe split vibration of the speaker diaphragm.

In addition, the wire-out end and the wire-in end of the voice coil areconnected to the FPCB 14, and conducted with the external circuitthrough the FPCB 14. This method makes the electrical connection of thevoice coil easier and has high reliability.

FIG. 1A is a SmartPA (smart power amplifier) test curve of theconventional diaphragm. FIG. 1B is a SmartPA test curve of a speakerdiaphragm according to an embodiment of the present invention.

Wherein, the abscissa is the test time (s), and the ordinate is thedisplacement (mm).

It should be noted that, in the embodiment of the present invention, thestructure of the conventional diaphragm is the same as the structure ofthe diaphragm in the embodiment of the present invention, and itsmaterial is different from that of the diaphragm in the embodiment ofthe present invention. For example, the conventional diaphragm and thediaphragm in the embodiment of the present invention are three-layerstructures, and the conventional diaphragm includes two PEEK surfacelayers and an adhesive layer located between the two surface layers. Thediaphragm of the embodiment of the present invention is also athree-layer structure, including two thermoplastic polyester elastomersurface layers and an adhesive layer located between the two surfacelayers. The thickness and structure of the corresponding adhesive layerof the two diaphragms are the same. The voice coils and the magneticcircuit systems connected with the two diaphragms are the same. Theconventional diaphragm structure and the diaphragm structure of thepresent invention for comparison in the following embodiments adopt thesame structure as the embodiment, and it will not be repeated.

When the electrical audio signal is input to the speaker, according toF=BIL, it can be known that when the design of the voice coil and themagnetic circuit system is fixed (the BL value is fixed), the voice coilis subjected to the same force of the electromagnetic field. Therefore,the driving force from the voice coil to the diaphragm is the same.

However, since the Young's modulus of PEEK is much greater than that ofthe diaphragm of the embodiment of the present invention, the diaphragmof the embodiment of the present invention is more prone to elasticdeformation under the same force, so as to achieve the desireddisplacement. It can be seen from the SmartPA test curves of the twodiaphragms that when the same music is played, the diaphragm of theembodiment of the present invention has a greater displacement duringthe vibration process, and thus the acquired loudness is also greater.

FIG. 5 is a test curve of the vibration displacements of different partsof the speaker diaphragm according to an embodiment of the presentinvention at different frequencies. FIG. 6 is a test curve of thevibration displacements of different parts of the conventional diaphragmat different frequencies.

Wherein, the diaphragm is a rectangular corrugated ring diaphragm. Theabscissa is the frequency (Hz), and the ordinate is the loudnessdisplacement (mm). The test is performed at the edge position and thecenter position of the central portion of the diaphragm.

It can be seen that the curves in FIG. 5 are more concentrated, whilethe curves in FIG. 6 are more dispersed. This shows that the vibrationconsistency of all parts of the speaker diaphragm of the embodiment ofthe present invention is better, and during the vibration process, theswing of the diaphragm is really less, and the sound quality and hearingstability are better.

FIG. 9 is a test curve of total harmonic distortion between a speakerdiaphragm according to an embodiment of the present invention and aconventional diaphragm. The diaphragm is a corrugated ring diaphragm.The abscissa is the frequency (Hz), and the ordinate is the totalharmonic distortion THD (%).

Wherein, the dotted line is the test curve of total harmonic distortionof the speaker diaphragm provided by the embodiment of the presentinvention. The solid line is the test curve of total harmonic distortionof the conventional PEEK diaphragm.

It can be seen from FIG. 9 that the speaker diaphragm of the embodimentof the present invention has a lower THD (total harmonic distortion)compared to the PEEK diaphragm, and has no peaks and the like. Thisshows that the speaker diaphragm of the embodiment of the presentinvention has a better anti-polarization ability and a better soundquality.

FIG. 10 is a test curve of loudness (SPL curve) of a speaker diaphragmaccording to an embodiment of the present invention and a conventionaldiaphragm at different frequencies. The diaphragm is a corrugated ringdiaphragm. The abscissa is frequency (Hz), and the ordinate is loudness.

Wherein, the dotted line is the test curve of the speaker diaphragmprovided by the embodiment of the present invention. The solid line isthe test curve of the conventional PEEK diaphragm.

It can be seen from the SPL curve in FIG. 10 that the mid-frequencyperformances of the two speaker diaphragms are similar. The F₀ of thespeaker using the diaphragm of the embodiment of the present inventionis 815 Hz, at c in FIG. 10 , and the F₀ of the speaker using PEEKdiaphragm is 860 Hz, at d in FIG. 10 . This shows that the low frequencysensitivity of the speaker diaphragm of the embodiment of the presentinvention is higher than that of the PEEK diaphragm. In other words, thespeaker adopting the speaker diaphragm of the embodiment of the presentinvention has higher loudness and comfort level.

According to another embodiment of the present invention, a speaker isprovided. The speaker includes a vibration system and a magnetic circuitsystem that cooperates with the vibration system. The vibration systemincludes the speaker diaphragm provided by the present invention. Forexample, the diaphragm is a corrugated ring diaphragm or a flat platediaphragm. The speaker has the characteristics of good sound generationeffect and good durability.

The F₀ of the speaker is proportional to the Young's modulus andthickness. The F₀ can be changed by changing the thickness and Young'smodulus of the speaker diaphragm. The specific adjustment principle isas follows:

${F0} = {\frac{1}{2\pi}\sqrt{\frac{1}{CmsMms}}}$wherein, Mms is the equivalent vibration quality of the speaker, and Cmsis the equivalent compliance of the speaker:

${Cms} = \frac{\left( {C_{m1}*C_{m2}} \right)}{\left( {C_{m1} + C_{m2}} \right)}$wherein, Cms1 is the damper compliance, and Cms2 is the diaphragmcompliance. When designing without damper, the equivalent compliance ofthe speaker is the diaphragm compliance:

$C_{m2} = \frac{\left( {1 - u^{3}} \right)W^{3}}{{\pi\left( {W + {dvc}} \right)}t^{3}{Ea}_{1}a_{2}}$wherein, w is the total width of the corrugated rim of the diaphragm, tis the thickness of the diaphragm; dvc is the fitting outer diameter ofthe diaphragm and voice coil; E is the Young's modulus of the diaphragmmaterial; u is the Poisson's ratio of the diaphragm material.

It can be seen that the F₀ of the speaker is proportional to the modulusand thickness. In order to acquire full bass and comfortable listening,the diaphragm should have sufficient stiffness and damping while thespeaker has a lower F₀. Those skilled in the art can adjust the size ofF₀ by adjusting the Young's modulus and thickness of the speakerdiaphragm. Preferably, the Young's modulus is 5-600 MPa. The thicknessof the speaker diaphragm is 10-100 μm. This enables the F₀ of thespeaker to reach 150-1500 Hz. The low frequency performance of thespeaker is excellent.

Preferably, the amplitude of the speaker diaphragm is 0.25 mm-1.0 mm,and the “amplitude” described in this embodiment refers to theunidirectional maximum value of the diaphragm deviation from the balanceposition. The speaker diaphragm containing the thermoplastic polyesterelastomer film layer still has a good hearing effect in this vibrationrange. However, the amplitude of engineering plastic films, such as PEEKfilm, generally cannot reach the above-mentioned range, and even if itcan reach the above-mentioned range, a good hearing effect cannot beachieved.

Further, the amplitude of the speaker diaphragm is 0.4 mm-0.6 mm. Thisrange enables the vibration system to achieve a better listening effectand have a sufficient space allowance for vibration.

Although some specific embodiments of the present invention have beendescribed in detail through examples, those skilled in the art shouldunderstand that the above examples are only for illustration and not forlimiting the scope of the present invention. It should be understood bya person skilled in the art that the above embodiments can be modifiedwithout departing from the scope and spirit of the present invention.The scope of the present invention is defined by the attached claims.

The invention claimed is:
 1. A speaker diaphragm comprising two surfacelayers compounded together and at least one intermediate layer locatedbetween the two surface layers, wherein at least one of the surfacelayers is a thermoplastic polyester elastomer film layer, at least oneof the intermediate layers is an adhesive layer, the thermoplasticpolyester elastomer is a copolymer including a polyester hard segment Aand a polyether or aliphatic polyester soft segment B, a thickness ofthe thermoplastic polyester elastomer film layer is 5-70 μm, and athickness of the adhesive layer is 1-40 μm.
 2. The speaker diaphragmaccording to claim 1, wherein the thermoplastic polyester elastomer filmlayer has a thickness of 5-40 μm.
 3. The speaker diaphragm according toclaim 1, wherein the the adhesive layer has a thickness of 2-35 μm. 4.The speaker diaphragm according to claim 1, wherein the speakerdiaphragm has a thickness of 10-100 μm.
 5. The speaker diaphragmaccording to claim 1, wherein the thermoplastic polyester elastomer hasa loss factor greater than or equal to 0.015.
 6. The speaker diaphragmaccording to claim 1, wherein the thermoplastic polyester elastomer filmlayer has an elastic recovery rate after 10% strain greater than orequal to 80%, and a percentage of breaking elongation of thethermoplastic polyester elastomer film layer is greater than or equal to300%.
 7. The speaker diaphragm according to claim 1, wherein an adhesiveforce between the adhesive layer and the thermoplastic polyesterelastomer film layer is greater than 100 g/25 mm (180° peeling).
 8. Thespeaker diaphragm according to claim 1, wherein a weight percentage ofthe polyester hard segment A is 10-95%, and a relative molecular weightof the polyether or aliphatic polyester soft segment B is 600-6000; thepolyether or aliphatic polyester soft segment B is selected from thegroup consisting of aliphatic polyester, polytetrahydrofuran ether,polyphenylene ether and polyethylene oxide, the polyester hard segment Acomprises a polymer of dibasic acid and dihydric alcohol, wherein thedibasic acid is selected from the group consisting of terephthalic acid,isophthalic acid, naphthalenedicarboxylic acid and biphenyldicarboxylicacid, and the dihydric alcohol is selected from the group consisting ofethylene glycol, propylene glycol, butylene glycol, pentanediol, andhexylene glycol.
 9. The speaker diaphragm according to claim 1, whereinthe polyester hard segment A comprises a material that can becrystallized, an average polymerization degree of the polyester hardsegment A material is ≥2, and a melting temperature of the polyesterhard segment A is ≥150° C.
 10. The speaker diaphragm according to claim1, wherein the two surface layers are the thermoplastic polyesterelastomer film layers.
 11. The speaker diaphragm according to claim 10,wherein the speaker diaphragm comprises a three-layer structureincluding one intermediate layer.
 12. The speaker diaphragm according toclaim 10, wherein the speaker diaphragm comprises two intermediatelayers, and the two intermediate layers comprise adhesive layers ofdifferent materials.
 13. The speaker diaphragm according to claim 10,wherein the speaker diaphragm comprises three intermediate layers,wherein a first and a second of the intermediate layers compriseadhesive layers and a third of the intermediate layers comprises thethermoplastic polyester elastomer film layer, and wherein thethermoplastic polyester elastomer film layer is located between the twoadhesive layers.
 14. The speaker diaphragm according to claim 10,wherein the speaker diaphragm comprises three intermediate layers,wherein the three intermediate layers comprise adhesive layers.
 15. Thespeaker diaphragm according to claim 1, wherein the two surface layershave the same thickness.
 16. A speaker, comprising a vibration systemand a magnetic circuit system cooperating with the vibration system,wherein the vibration system comprises the speaker diaphragm accordingto claim 1.